A number of (as yet unfulfilled) energy and environmental policy pledges have been removed from the WhiteHouse.gov page in recent weeks.

Chief among them: President Obama's pledge to "invest $150 billion over ten years in energy research and development to transition to a clean energy economy," once a central plank in Obama's energy and environment platform, and a feature of his first national budget proposal (in FY2009).

The new page features a short (rhetorical) introduction, followed by a list of White House accomplishments in the realm of energy and environment, and no longer features any forward-looking pledges.

That includes any clear pledge to reduce U.S. greenhouse gas emissions by any particular amount by any particular date, or to establish a cap and trade program to achieve those objectives, other signatures of Obama's earlier policy pledges in the area. Cap and trade legislation is now widely considered dead in the U.S. Senate, after failing to secure anything close to the sixty-vote super-majority needed to clear the chamber.

One could read the changes at WhiteHouse.gov as a simple reflection of where Obama now is in his presidency, with almost two years under his belt and a list of accomplishments to his name to replace a set of campaign-style promises. Equally notable, however, is the list of what has indeed been accomplished, and what, for now, remains an entirely unfulfilled promise.

Here's the back story. During his election campaign, Obama pledged to invest $150 billion over 10 years in research and development to advance non-polluting energy technologies. That level of federal investment on energy frontiers, after decades of bipartisan disinterest in energy sciences, has been widely seen as a critical component of any meaningful effort to expand the world's energy menu without overloading the atmosphere with heat-trapping gases.

But nearly all of the research money under the Obama plan was slated to come from the revenues generated by auctioning permits for greenhouse gas emissions. So the fate of the new American post-fossil energy revolution was tied to the fate of a cap-and-trade system that was always going to be a tough sell in a polarized Congress and now is on the legislative scrap heap.

The Web site changes came with little fanfare at the same time environmental groups were pleading with Obama to take a more proactive role in finding the votes for a sweeping climate bill. The president's primetime address from the Oval Office on June 15 drew criticism from activists when he didn't mention the words "carbon," "greenhouse gases," "global warming" or "cap and trade."